This invention relates to steering mechanisms and more particularly to a configuration adapted for use in a strut type forward landing gear of an aircraft.
The telescoping strut type landing gear to which the invention relates is of a configuration well known in the aircraft industry. Likewise, the mounting of actuators between a nonrotating structure and a steering collar attached to a rotatable wheel structure is known in the art. For example, such a configuration appears in U.S. Pat. No. 2,930,547. Another approach for creating a steering torque in a strut type landing gear is disclosed in U.S. Pat. No. 2,943,818. Here the inventors show an apparatus in the form of a steering motor consisting of a multiple cam steering collar upon which three piston actuated followers press. Though this apparatus allows rotation of the landing gear through a full 360 degrees with a constant level of output torque, no compensation is provided to offset load increases associated with increases in the steering angle. Furthermore, the instantaneous magnitude of output torque produced by this mechanization is the result of only one actuation piston with the remaining two in either a neutral or an opposing mode of operation.
The invention contained herein was devised in response to a torque inadequacy problem in the steering of the YC-14 phototype aircraft front landing gear. It was found that the existing two piston steering mechanization, similar to that shown in U.S. Pat. No. 2,930,547 lacked adequate torque when the steering approached the limits of 60 degrees either direction from forward. Attempts to improve the steering performance by varying the geometry while retaining a dual actuator system were unsuccessful, due in part to constraints imposed by the landing gear configuration and hydraulic system limitations.